Flexural buckling of cold-drawn oxygen-free copper tubular columns with circular hollow sections under axial compression

Cold-Formed Steel (CFS) is a good construction material because of its high strength-to-weight ratio, that is, it exhibits efficient load carrying capabilities in combination with its lightweight characteristics. Although CFS is already being used in construction, information on structural performance of locally-produced CFS in the Philippines is scarce. To date, the authors have not found any experimental study done in the Philippines regarding the structural performance of locally-produced CFS. In this study, C-section and Z-section are being studied since these members exhibit buckling failures that may be difficult to predict due to complexity of their section geometry. The objective of this paper is to present the performance of these CFS sections when subjected to concentric axial compression both experimentally and computationally. For the experimental part, the CFS members were subjected to axial compression using a hydraulic jack. High-speed video cameras were used to capture the different failure modes. For the computational aspect, provisions found in the National Structural Code of the Philippines (NSCP) were used to calculate the compression strength of the members. A total of 80 C-section specimens with 5 different lengths and 5 different thicknesses were tested. It was found that the strength calculations using the NSCP provisions were not consistent with the results of the compression tests. For shorter lengths, distortional buckling prevailed as the main failure, while for longer lengths, torsional-flexural buckling occurred. All of the predicted strengths were highly conservative. For the Z-section, a total of 180 specimens with 6 different lengths and 6 different thicknesses were tested. Torsional-flexural buckling was observed in majority of the specimens. Although most of the failure modes were predicted correctly, it was found that the predicted strengths using the NSCP were relatively high compared to the experimental results, thus non-conservative. Finite Element Method (FEM) analyses using ANSYS were conducted. Findings indicate that the experiment results agreed well with the FEM results.

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Study on shear capacity of connections with external stiffening rings between square steel tubular columns and steel beams

Advances in Structural Engineering ◽

10.1177/1369433220956832 ◽

2020 ◽

pp. 136943322095683

Author(s):

Bin Rong ◽

Lei Wang ◽

Ruoyu Zhang

Keyword(s):

Finite Element ◽

Axial Compression ◽

Compression Ratio ◽

Shear Behavior ◽

Steel Tube ◽

Shear Capacity ◽

Steel Beams ◽

Tubular Columns ◽

Axial Compression Ratio ◽

Panel Zone

This paper studied the shear behavior of the connections with external stiffening rings between square steel tubular columns and steel beams by experimental, numerical and analytical methods. Two connections with external stiffening rings were tested under low cyclic loading to investigate the effect of axial compression ratio on the shear behavior and capacity of the connection. The test result showed that the change of the axial compression ratio had little effect on the shear capacity of the connection while the ductility of the connection was decreasing with the increase of the axial compression ratio. Seven nonlinear finite element models were designed to investigate the seismic behavior of the connection under cyclic test. Parametric studies are carried out to study the influence of the following parameters on the shearing capacity and deformation in panel zone: the width and the height of the steel tube in panel zone and the thickness of the external stiffening rings. Finally, based on the model considering the post-buckling strength of the web of the steel tube in panel zone, a calculation formula was fitted by the results of the finite element simulation.

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Influence of Inner Steel Tube Diameter on Compressive Behavior of Square FRP-HSC-Steel Double-Skin Tubular Columns

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1119.688 ◽

2015 ◽

Vol 1119 ◽

pp. 688-693 ◽

Cited By ~ 1

Author(s):

Butje Alfonsius Louk Fanggi ◽

Togay Ozbakkloglu

Keyword(s):

Axial Compression ◽

Axial Stress ◽

Steel Tube ◽

Tube Diameter ◽

Experimental Program ◽

Composite Columns ◽

Tubular Columns ◽

Column System ◽

Double Skin ◽

The University

FRP-concrete-steel double-skin tubular columns (DSTCs) are a new form composite column system that effectively combines the advantages of the constituent materials. The performance of this column system has been experimentally investigated in a number of recent studies. However, apart from a single study reported on square DSTCs, all of the existing studies have been concerned with DSTCs with circular external tubes. This paper reports on part of an ongoing experimental program at the University of Adelaide on FRP-concrete-steel composite columns. The results from 12 square hollow and concrete-filled DSTCs and six companion hollow concrete-filled FRP tubes (H-CFFTs) that were tested under axial compression are presented. Results of the experimental study indicate that hollow DSTCs with larger inner steel tube diameters develop similar ultimate axial stresses to but significantly larger axial strains than companion DSTCs with smaller inner steel tubes. The results also show that, in concrete-filled DSTCs with similar Ds/ts ratios, an increase in the steel tube diameter leads to an increase in both axial stress and strain of concrete. It was observed that H-CFFTs perform significantly worse than both hollow and filled DSTCs under axial compression, and their behavior further degrades with an increase in the diameter of their inner voids.

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